IDENTIFICATION OF MULTIPLE PROLIFERATIVE GROWTH-FACTORS IN BREAST CYST FLUID

Gross cystic disease is a common benign breast disease that is associa ted with a twofold to fourfold increase in breast cancer risk. Both di seases are hormonally induced and may share a common biochemical envir onment conducive to abnormal proliferative responses. A large collecti on of breast cyst fluid samples was analyzed for growth factors associ ated with cell proliferation: epidermal growth factor (EGF), insulin-l ike growth factor I (IGF-I), insulin-like growth factor II (IGF-II), p latelet-derived growth factor (PDGF), transforming growth factor-alpha (TGF-alpha), and transforming growth factor-beta (TGF-beta). The data demonstrate that significant amounts of proliferative growth factors are present in breast cyst fluid of all cyst subtypes. The presence of IGF-II, PDGF, and TGF-beta in breast cyst fluid was confirmed for the first time. EGF, PDGF, and TGF-beta concentrations in breast cyst flu id were several times greater than reported for serum; IGF-I and IGF-I I concentrations were several times lower. In the first 100 samples te sted, no TGF-alpha was detected. Only EGF and IGF-II levels demonstrat ed a consistent correlation with apocrine type I cysts. These results demonstrated that effective concentrations of proliferative growth fac tors are in breast cyst fluid and suggest that adjacent breast tissue may be a probable source of synthesis. Growth factor profiles of breas t cyst fluid may indicate the presence in breast tissue of a hormonal and proliferative environment permissive to subsequent cancer growth.